EFFECT OF CHITOSAN AND CHITOSAN GLUTAMATE ENHANCING THE DISSOLUTION PROPERTIES OF THE POORLY WATER-SOLUBLE DRUG NIFEDIPINE

In this study, a significant effect of chitosan increasing nifedipine dissolution has been demonstrated. This effect was dependent on the po lymer:drug mixing weight ratio, the chitosan type and the method used to disperse the drug within the polymer. The greater the chitosan cont ent the higher the drug dissolution was, up to a maximum corresponding to a polymer:drug ratio of 3.1. Significant differences within the va rious tested chitosans were observed. The lower the M-w the more impor tant the polymer effect was which, in turn, was more noticeable for th e glutamate salt than for the chitosan base. The various chitosan:nife dipine solid mixtures were ordered, according to the efficiency of imp roving the drug dissolution, as follows: solid dispersion > kneaded mi xture > co-ground mixture > physical mixture. The drug dissolution enh ancement was attributed to the decreased drug crystallinity and size a nd polymer wetting effect. Go-grinding of chitosan along with nifedipi ne in a 3:1 ratio, which leads to solid mixtures exhibiting a signific antly improved dissolution profile without requiring the addition of o rganic solvents or high temperatures for its preparation, appears to b e the more simple and convenient method. (C) 1998 Elsevier Science B.V . All rights reserved.